fs_mgr.c revision c1bf89663ca71949b508007d4df2b5b06038f96d 
1/*
2 * Copyright (C) 2012 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17/* TO DO:
18 *   1. Re-direct fsck output to the kernel log?
19 *
20 */
21
22#include <stdio.h>
23#include <stdlib.h>
24#include <string.h>
25#include <unistd.h>
26#include <fcntl.h>
27#include <ctype.h>
28#include <sys/mount.h>
29#include <sys/stat.h>
30#include <errno.h>
31#include <sys/types.h>
32#include <sys/wait.h>
33#include <libgen.h>
34#include <time.h>
35
36#include <private/android_filesystem_config.h>
37#include <cutils/partition_utils.h>
38#include <cutils/properties.h>
39
40#include "fs_mgr_priv.h"
41
42#define KEY_LOC_PROP   "ro.crypto.keyfile.userdata"
43#define KEY_IN_FOOTER  "footer"
44
45#define E2FSCK_BIN      "/system/bin/e2fsck"
46
47struct flag_list {
48    const char *name;
49    unsigned flag;
50};
51
52static struct flag_list mount_flags[] = {
53    { "noatime",    MS_NOATIME },
54    { "noexec",     MS_NOEXEC },
55    { "nosuid",     MS_NOSUID },
56    { "nodev",      MS_NODEV },
57    { "nodiratime", MS_NODIRATIME },
58    { "ro",         MS_RDONLY },
59    { "rw",         0 },
60    { "remount",    MS_REMOUNT },
61    { "defaults",   0 },
62    { 0,            0 },
63};
64
65static struct flag_list fs_mgr_flags[] = {
66    { "wait",        MF_WAIT },
67    { "check",       MF_CHECK },
68    { "encryptable=",MF_CRYPT },
69    { "defaults",    0 },
70    { 0,             0 },
71};
72
73/*
74 * gettime() - returns the time in seconds of the system's monotonic clock or
75 * zero on error.
76 */
77static time_t gettime(void)
78{
79    struct timespec ts;
80    int ret;
81
82    ret = clock_gettime(CLOCK_MONOTONIC, &ts);
83    if (ret < 0) {
84        ERROR("clock_gettime(CLOCK_MONOTONIC) failed: %s\n", strerror(errno));
85        return 0;
86    }
87
88    return ts.tv_sec;
89}
90
91static int wait_for_file(const char *filename, int timeout)
92{
93    struct stat info;
94    time_t timeout_time = gettime() + timeout;
95    int ret = -1;
96
97    while (gettime() < timeout_time && ((ret = stat(filename, &info)) < 0))
98        usleep(10000);
99
100    return ret;
101}
102
103static int parse_flags(char *flags, struct flag_list *fl, char **key_loc,
104                       char *fs_options, int fs_options_len)
105{
106    int f = 0;
107    int i;
108    char *p;
109    char *savep;
110
111    /* initialize key_loc to null, if we find an MF_CRYPT flag,
112     * then we'll set key_loc to the proper value */
113    if (key_loc) {
114        *key_loc = NULL;
115    }
116    /* initialize fs_options to the null string */
117    if (fs_options && (fs_options_len > 0)) {
118        fs_options[0] = '\0';
119    }
120
121    p = strtok_r(flags, ",", &savep);
122    while (p) {
123        /* Look for the flag "p" in the flag list "fl"
124         * If not found, the loop exits with fl[i].name being null.
125         */
126        for (i = 0; fl[i].name; i++) {
127            if (!strncmp(p, fl[i].name, strlen(fl[i].name))) {
128                f |= fl[i].flag;
129                if ((fl[i].flag == MF_CRYPT) && key_loc) {
130                    /* The encryptable flag is followed by an = and the
131                     * location of the keys.  Get it and return it.
132                     */
133                    *key_loc = strdup(strchr(p, '=') + 1);
134                }
135                break;
136            }
137        }
138
139        if (!fl[i].name) {
140            if (fs_options) {
141                /* It's not a known flag, so it must be a filesystem specific
142                 * option.  Add it to fs_options if it was passed in.
143                 */
144                strlcat(fs_options, p, fs_options_len);
145                strlcat(fs_options, ",", fs_options_len);
146            } else {
147                /* fs_options was not passed in, so if the flag is unknown
148                 * it's an error.
149                 */
150                ERROR("Warning: unknown flag %s\n", p);
151            }
152        }
153        p = strtok_r(NULL, ",", &savep);
154    }
155
156out:
157    if (fs_options && fs_options[0]) {
158        /* remove the last trailing comma from the list of options */
159        fs_options[strlen(fs_options) - 1] = '\0';
160    }
161
162    return f;
163}
164
165/* Read a line of text till the next newline character.
166 * If no newline is found before the buffer is full, continue reading till a new line is seen,
167 * then return an empty buffer.  This effectively ignores lines that are too long.
168 * On EOF, return null.
169 */
170static char *getline(char *buf, int size, FILE *file)
171{
172    int cnt = 0;
173    int eof = 0;
174    int eol = 0;
175    int c;
176
177    if (size < 1) {
178        return NULL;
179    }
180
181    while (cnt < (size - 1)) {
182        c = getc(file);
183        if (c == EOF) {
184            eof = 1;
185            break;
186        }
187
188        *(buf + cnt) = c;
189        cnt++;
190
191        if (c == '\n') {
192            eol = 1;
193            break;
194        }
195    }
196
197    /* Null terminate what we've read */
198    *(buf + cnt) = '\0';
199
200    if (eof) {
201        if (cnt) {
202            return buf;
203        } else {
204            return NULL;
205        }
206    } else if (eol) {
207        return buf;
208    } else {
209        /* The line is too long.  Read till a newline or EOF.
210         * If EOF, return null, if newline, return an empty buffer.
211         */
212        while(1) {
213            c = getc(file);
214            if (c == EOF) {
215                return NULL;
216            } else if (c == '\n') {
217                *buf = '\0';
218                return buf;
219            }
220        }
221    }
222}
223
224static struct fstab_rec *read_fstab(char *fstab_path)
225{
226    FILE *fstab_file;
227    int cnt, entries;
228    int len;
229    char line[256];
230    const char *delim = " \t";
231    char *save_ptr, *p;
232    struct fstab_rec *fstab;
233    char *key_loc;
234#define FS_OPTIONS_LEN 1024
235    char tmp_fs_options[FS_OPTIONS_LEN];
236
237    fstab_file = fopen(fstab_path, "r");
238    if (!fstab_file) {
239        ERROR("Cannot open file %s\n", fstab_path);
240        return 0;
241    }
242
243    entries = 0;
244    while (getline(line, sizeof(line), fstab_file)) {
245        /* if the last character is a newline, shorten the string by 1 byte */
246        len = strlen(line);
247        if (line[len - 1] == '\n') {
248            line[len - 1] = '\0';
249        }
250        /* Skip any leading whitespace */
251        p = line;
252        while (isspace(*p)) {
253            p++;
254        }
255        /* ignore comments or empty lines */
256        if (*p == '#' || *p == '\0')
257            continue;
258        entries++;
259    }
260
261    if (!entries) {
262        ERROR("No entries found in fstab\n");
263        return 0;
264    }
265
266    fstab = calloc(entries + 1, sizeof(struct fstab_rec));
267
268    fseek(fstab_file, 0, SEEK_SET);
269
270    cnt = 0;
271    while (getline(line, sizeof(line), fstab_file)) {
272        /* if the last character is a newline, shorten the string by 1 byte */
273        len = strlen(line);
274        if (line[len - 1] == '\n') {
275            line[len - 1] = '\0';
276        }
277
278        /* Skip any leading whitespace */
279        p = line;
280        while (isspace(*p)) {
281            p++;
282        }
283        /* ignore comments or empty lines */
284        if (*p == '#' || *p == '\0')
285            continue;
286
287        /* If a non-comment entry is greater than the size we allocated, give an
288         * error and quit.  This can happen in the unlikely case the file changes
289         * between the two reads.
290         */
291        if (cnt >= entries) {
292            ERROR("Tried to process more entries than counted\n");
293            break;
294        }
295
296        if (!(p = strtok_r(line, delim, &save_ptr))) {
297            ERROR("Error parsing mount source\n");
298            return 0;
299        }
300        fstab[cnt].blk_dev = strdup(p);
301
302        if (!(p = strtok_r(NULL, delim, &save_ptr))) {
303            ERROR("Error parsing mnt_point\n");
304            return 0;
305        }
306        fstab[cnt].mnt_point = strdup(p);
307
308        if (!(p = strtok_r(NULL, delim, &save_ptr))) {
309            ERROR("Error parsing fs_type\n");
310            return 0;
311        }
312        fstab[cnt].type = strdup(p);
313
314        if (!(p = strtok_r(NULL, delim, &save_ptr))) {
315            ERROR("Error parsing mount_flags\n");
316            return 0;
317        }
318        tmp_fs_options[0] = '\0';
319        fstab[cnt].flags = parse_flags(p, mount_flags, 0, tmp_fs_options, FS_OPTIONS_LEN);
320
321        /* fs_options are optional */
322        if (tmp_fs_options[0]) {
323            fstab[cnt].fs_options = strdup(tmp_fs_options);
324        } else {
325            fstab[cnt].fs_options = NULL;
326        }
327
328        if (!(p = strtok_r(NULL, delim, &save_ptr))) {
329            ERROR("Error parsing fs_mgr_options\n");
330            return 0;
331        }
332        fstab[cnt].fs_mgr_flags = parse_flags(p, fs_mgr_flags, &key_loc, 0, 0);
333        fstab[cnt].key_loc = key_loc;
334
335        cnt++;
336    }
337    fclose(fstab_file);
338
339    return fstab;
340}
341
342static void free_fstab(struct fstab_rec *fstab)
343{
344    int i = 0;
345
346    while (fstab[i].blk_dev) {
347        /* Free the pointers return by strdup(3) */
348        free(fstab[i].blk_dev);
349        free(fstab[i].mnt_point);
350        free(fstab[i].type);
351        free(fstab[i].fs_options);
352        free(fstab[i].key_loc);
353
354        i++;
355    }
356
357    /* Free the actual fstab array created by calloc(3) */
358    free(fstab);
359}
360
361static void check_fs(char *blk_dev, char *type)
362{
363    pid_t pid;
364    int status;
365
366    /* Check for the types of filesystems we know how to check */
367    if (!strcmp(type, "ext2") || !strcmp(type, "ext3") || !strcmp(type, "ext4")) {
368        INFO("Running %s on %s\n", E2FSCK_BIN, blk_dev);
369        pid = fork();
370        if (pid > 0) {
371            /* Parent, wait for the child to return */
372            waitpid(pid, &status, 0);
373        } else if (pid == 0) {
374            /* child, run checker */
375            execlp(E2FSCK_BIN, E2FSCK_BIN, "-y", blk_dev, (char *)NULL);
376
377            /* Only gets here on error */
378            ERROR("Cannot run fs_mgr binary %s\n", E2FSCK_BIN);
379        } else {
380            /* No need to check for error in fork, we can't really handle it now */
381            ERROR("Fork failed trying to run %s\n", E2FSCK_BIN);
382        }
383    }
384
385    return;
386}
387
388static void remove_trailing_slashes(char *n)
389{
390    int len;
391
392    len = strlen(n) - 1;
393    while ((*(n + len) == '/') && len) {
394      *(n + len) = '\0';
395      len--;
396    }
397}
398
399static int fs_match(char *in1, char *in2)
400{
401    char *n1;
402    char *n2;
403    int ret;
404
405    n1 = strdup(in1);
406    n2 = strdup(in2);
407
408    remove_trailing_slashes(n1);
409    remove_trailing_slashes(n2);
410
411    ret = !strcmp(n1, n2);
412
413    free(n1);
414    free(n2);
415
416    return ret;
417}
418
419int fs_mgr_mount_all(char *fstab_file)
420{
421    int i = 0;
422    int encrypted = 0;
423    int ret = -1;
424    int mret;
425    struct fstab_rec *fstab = 0;
426
427    if (!(fstab = read_fstab(fstab_file))) {
428        return ret;
429    }
430
431    for (i = 0; fstab[i].blk_dev; i++) {
432        if (fstab[i].fs_mgr_flags & MF_WAIT) {
433            wait_for_file(fstab[i].blk_dev, WAIT_TIMEOUT);
434        }
435
436        if (fstab[i].fs_mgr_flags & MF_CHECK) {
437            check_fs(fstab[i].blk_dev, fstab[i].type);
438        }
439
440        mret = mount(fstab[i].blk_dev, fstab[i].mnt_point, fstab[i].type,
441                     fstab[i].flags, fstab[i].fs_options);
442        if (!mret) {
443            /* Success!  Go get the next one */
444            continue;
445        }
446
447        /* mount(2) returned an error, check if it's encrypted and deal with it */
448        if ((fstab[i].fs_mgr_flags & MF_CRYPT) && !partition_wiped(fstab[i].blk_dev)) {
449            /* Need to mount a tmpfs at this mountpoint for now, and set
450             * properties that vold will query later for decrypting
451             */
452            if (mount("tmpfs", fstab[i].mnt_point, "tmpfs",
453                  MS_NOATIME | MS_NOSUID | MS_NODEV, CRYPTO_TMPFS_OPTIONS) < 0) {
454                ERROR("Cannot mount tmpfs filesystem for encrypted fs at %s\n",
455                        fstab[i].mnt_point);
456                goto out;
457            }
458            encrypted = 1;
459        } else {
460            ERROR("Cannot mount filesystem on %s at %s\n",
461                    fstab[i].blk_dev, fstab[i].mnt_point);
462            goto out;
463        }
464    }
465
466    if (encrypted) {
467        ret = 1;
468    } else {
469        ret = 0;
470    }
471
472out:
473    free_fstab(fstab);
474    return ret;
475}
476
477/* If tmp_mnt_point is non-null, mount the filesystem there.  This is for the
478 * tmp mount we do to check the user password
479 */
480int fs_mgr_do_mount(char *fstab_file, char *n_name, char *n_blk_dev, char *tmp_mnt_point)
481{
482    int i = 0;
483    int ret = -1;
484    struct fstab_rec *fstab = 0;
485    char *m;
486
487    if (!(fstab = read_fstab(fstab_file))) {
488        return ret;
489    }
490
491    for (i = 0; fstab[i].blk_dev; i++) {
492        if (!fs_match(fstab[i].mnt_point, n_name)) {
493            continue;
494        }
495
496        /* We found our match */
497        /* First check the filesystem if requested */
498        if (fstab[i].fs_mgr_flags & MF_WAIT) {
499            wait_for_file(fstab[i].blk_dev, WAIT_TIMEOUT);
500        }
501
502        if (fstab[i].fs_mgr_flags & MF_CHECK) {
503            check_fs(fstab[i].blk_dev, fstab[i].type);
504        }
505
506        /* Now mount it where requested */
507        if (tmp_mnt_point) {
508            m = tmp_mnt_point;
509        } else {
510            m = fstab[i].mnt_point;
511        }
512        if (mount(n_blk_dev, m, fstab[i].type,
513                  fstab[i].flags, fstab[i].fs_options)) {
514            ERROR("Cannot mount filesystem on %s at %s\n",
515                    n_blk_dev, m);
516            goto out;
517        } else {
518            ret = 0;
519            goto out;
520        }
521    }
522
523    /* We didn't find a match, say so and return an error */
524    ERROR("Cannot find mount point %s in fstab\n", fstab[i].mnt_point);
525
526out:
527    free_fstab(fstab);
528    return ret;
529}
530
531/*
532 * mount a tmpfs filesystem at the given point.
533 * return 0 on success, non-zero on failure.
534 */
535int fs_mgr_do_tmpfs_mount(char *n_name)
536{
537    int ret;
538
539    ret = mount("tmpfs", n_name, "tmpfs",
540                MS_NOATIME | MS_NOSUID | MS_NODEV, CRYPTO_TMPFS_OPTIONS);
541    if (ret < 0) {
542        ERROR("Cannot mount tmpfs filesystem at %s\n", n_name);
543        return -1;
544    }
545
546    /* Success */
547    return 0;
548}
549
550int fs_mgr_unmount_all(char *fstab_file)
551{
552    int i = 0;
553    int ret = 0;
554    struct fstab_rec *fstab = 0;
555
556    if (!(fstab = read_fstab(fstab_file))) {
557        return -1;
558    }
559
560    while (fstab[i].blk_dev) {
561        if (umount(fstab[i].mnt_point)) {
562            ERROR("Cannot unmount filesystem at %s\n", fstab[i].mnt_point);
563            ret = -1;
564        }
565        i++;
566    }
567
568    free_fstab(fstab);
569    return ret;
570}
571/*
572 * key_loc must be at least PROPERTY_VALUE_MAX bytes long
573 *
574 * real_blk_dev must be at least PROPERTY_VALUE_MAX bytes long
575 */
576int fs_mgr_get_crypt_info(char *fstab_file, char *key_loc, char *real_blk_dev, int size)
577{
578    int i = 0;
579    struct fstab_rec *fstab = 0;
580
581    if (!(fstab = read_fstab(fstab_file))) {
582        return -1;
583    }
584    /* Initialize return values to null strings */
585    if (key_loc) {
586        *key_loc = '\0';
587    }
588    if (real_blk_dev) {
589        *real_blk_dev = '\0';
590    }
591
592    /* Look for the encryptable partition to find the data */
593    for (i = 0; fstab[i].blk_dev; i++) {
594        if (!(fstab[i].fs_mgr_flags & MF_CRYPT)) {
595            continue;
596        }
597
598        /* We found a match */
599        if (key_loc) {
600            strlcpy(key_loc, fstab[i].key_loc, size);
601        }
602        if (real_blk_dev) {
603            strlcpy(real_blk_dev, fstab[i].blk_dev, size);
604        }
605        break;
606    }
607
608    free_fstab(fstab);
609    return 0;
610}
611
612